http://www.glab.com.pl/true_bypass_wah-pad_en
http://www.glab.com.pl/img/user_manual_tbwp08042008.pdf
It reminds me of the circuitry that the bad horsie has.
They also make controller cables for various amps, including the JSX.
http://www.glab.com.pl/accessories
Jimmy
P.S.: I wonder if those cables would work with midi foot controllers?